Having an open marriage, as ref suggests, isn't really a lifestyle. This is a common debate. I tend to think polyamory is a "love style," or relationship choice or identity. There are many ways to do open relationships and polyamory.
By this lifestyle I mean an open marriage. We have discussed seeing other people. At first it was him just wanting me to be with others, but I told him my guilt would be too overwhelming if it was just me doing this, and not him, so I was able to have him consider being with others, as well. My expectations are I am hopeful in a way that it brings us closer. While we love each other deeply, our intimate relationship has always been lacking, I am hopeful that sharing our experiences with others will add a layer to our relationship that will strengthen it. And admittedly, I am hoping this allows me to experience some things that I have not been able to with him.
It sounds like your husband is turned on by the idea of you being with another man. And you seem to suggest your sex life has been lacking and this arrangement is being tried to "spice things up."
You don't really want to be with another guy, but after much fantasizing, maybe even close to coercion on your husband's part, you've been worn down enough to agree.
While this may seem fun as a fantasy (for him), reality never matches fantasy. That's a big red flag.
Opening a relationship should only be done if both partners are fully on board and excited for it for themselves individually. AND, if a relationship/marriage is strained in any way, opening it will shine on a light on your deeper problems.
You don't have to share intimate details here of what makes your sex life feel lacking. But you can if you want to. It might help. Or you two could seek some couples counseling to work on the disconnect. A new lover should not be used as a "Band-Aid" to patch up an existing problem. New people are not tools, they are human beings with feelings of their own.
In any case, if you're just opening to spice things up, is it really polyamory that you want? That is this board's focus, not just "open relationships" with casual sex. That is more akin to swinging. Swingers do use the euphemism "lifestyle" to describe their casual sexual activities. Maybe you are confused.
Polyamory means "many loves." It expects people to fall in love with multiple partners, to form romantic one-on-one, yet simultaneous couple bonds. Poly folk don't necessarily do group sex, aren't necessarily into voyeurism, exhibitionism, sharing intimate details of what they did with their bf with their husband, etc.
If you're bored with your h as a sex partner, opening up will give you more variety of sexual experiences. But beware... feelings could and very well might, develop, if your new partner(s) are more fulfilling sexually for you. Then what?
Yes, sorry that was a typo that I corrected. I meant to say my.
I'd suggest going to our resources list...
... and reading a few basic books on polyamory and opening up. In fact, the book
Opening Up is a great read. It addresses open relationships, swinging and polyamory, delves into the differences, and offers tons of tips on how not to screw this up.